Porch Roof Skylight

I'm looking for suggestions from the GBA readers for a cost effective way to let some light in through a farmer's porch roof. I am currently in the process of building my house which includes a farmers porch on the front/south face of the building. The roof is in front of the kitchen and dining area. I'd like to add some light to these rooms, particularly in the winter but block unwanted solar gain in the summer. My initial thought was to install a skylight and locate it strategically for solar gain in the winter but not in the summer. Since the unit would be installed in a open air porch it need not be operable or even energy efficient (if single pane glass units existed I'd go with that). Maybe the cost of a skylight is unnecessary? Perhaps I could build my own frame and install a pane of plexiglass? Is that too cheap/cheesy looking? Any suggestions to accomplish my goal would be greatly appreciated!